Page 161 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

136 CHAPTER 1

VetBooks.ir OSTEOCHONDRAL FRAGMENTATION lameness and pain/swelling of the palmar/plantar
AND PALMAR/PLANTAR EMINENCE
fetlock.
FRACTURES OF PROXIMAL P1
Differential diagnosis
Definition/overview OCD; PSB fracture.
Discrete osteochondral fragmentation of the proximal
phalanx occurs either dorsally or palmarly/plantarly. Diagnosis
Palmar/plantar eminence fractures describe acute Diagnosis is usually based on standard radiographic
traumatic avulsion fractures of the palmar or, more evaluation, although a different angulation may be
commonly, the plantar eminence of proximal P1. required to demonstrate the fragment and its con-
figuration. Osteochondral fragments of dorsoproxi-
Aetiology/pathophysiology mal P1 are demonstrated as discrete osseous bodies
Osteochondral fragmentation was originally thought on the medial or lateral proximal rim of P1, usually
to be a manifestation of OCD, but current opinion uniaxially but occasionally biaxially (Figs. 1.241,
is that it has a traumatic origin since histological evi- 1.242). Palmaro/plantaroproximal osteochondral
dence of OCD is lacking. Fragments may be clini- fragments of P1 can be described as axial or abaxial
cally silent and found on survey radiographs or may and may be articular/non-articular and often seen in
contribute to lameness, particularly at high speed. the hindlimbs (Figs. 1.243, 1.244). Acute fractures
Acute fracture of the palmar/plantar eminence of P1 of the palmar/plantar eminence present as articu-
is usually traumatic in origin. lar or, occasionally, non-articular bony fragments
with sharp marginations and degree of distraction
Clinical presentation through the insertion of the distal sesamoidean liga-
Horses with osteochondral fragmentation may pres- ments or proximal digital annular ligament. With
ent with joint effusion and/or lameness related to the osteochondral fragmentation, radiography of the
fetlock joint. Frequently, there are little clinical signs contralateral limb is recommended.
localising to the fetlock and diagnostic analgesia is
important to determine the clinical significance of Management
the finding of an osteochondral fragment. Horses Cases can be managed conservatively, particularly if
with an acute fracture of the palmar/plantar emi- the clinical significance of a fragment is question-
nence of proximal P1 usually present with acute able. However, removal of the fragment is frequently

1.241 1.242

Figs. 1.241, 1.242
(1.241) Lateromedial
radiograph of a fetlock joint
showing a small rounded
osteochondral fragment
off the proximal aspect of
P1. (1.242) Dorsolateral/
palmaromedial view
confirming it has arisen
from the dorsomedial
aspect.